It is imperative to prevent and mitigate oil well blowouts because they present great risk to human life and damage the environment. These and other types of spills pose large environmental clean-up costs and socio-economic upheaval. The problems are particularly acute when uncontrolled flow results from off-shore oil wells. It has been generally established in the petroleum industry that a series of large valve systems, termed a blowout preventer, should be positioned in-line with the wellhead to provide primary and secondary systems to stop the flow of oil under blowout conditions. Blowout preventers may be regarded as failsafe designs in a limited sense. That is, when one valve system fails to actuate as intended, one or more secondary valve systems are available as back-ups to reduce the risk that uncontrolled flow will continue unabated. This, of course, presumes that standard inspections and established procedures are followed and that the valves are properly maintained.
With occurrence of human fatalities and economic and environmental disasters, due to uncontrolled spills, additional solutions should be made available which quickly seal well bores and other flow paths in the event a blowout preventer malfunctions or when a spill occurs due to other causes. With respect to well bores, a number of conventional approaches are available to close the well when the blowout preventer malfunctions, these including use of a containment dome, connection of a riser insertion tube or injection of dense material into the blowout preventer followed by sealing the well with cement. As one example, it has at times been effective to counter the pressure at the well head to perform what is referred to as a top kill. In this procedure dense material is pumped down the drill string or through a secondary line which bypasses the blowout preventer. The resulting downward pressure can prevent upward movement of oil and gas. The foregoing solutions have, at times, been effective in particular contexts, but none of these have provided a universal solution to rapidly abate the toxic flow of petroleum products into bodies of water. Similarly when the wall of a tank or other reservoir, or the wall of a land or sea transport vessel is compromised, there is a need to quickly seal the wall in order to mitigate flow of petroleum products or toxic chemicals into the environment.